The present invention relates to fluid couplings, and more particularly to a fluid coupling for use in fluid control devices for manufacturing semiconductors, the fluid coupling being useful for interconnecting massflow controllers, on-off valves, and connecting blocks interposed between these devices.
Fluid control devices for use in manufacturing semiconductors comprise a regulator such as massflow controller for controlling the rate of flow or a pressure regulator, and an on-off valve in combination with the regulator. It is known to connect the massflow controller to the on-off valve by a suitable connecting block as a preferred arrangement (see JP-A No. 326943/1996). FIG. 10 shows the construction of a fluid coupling included in the arrangement.
With reference to FIG. 10, the fluid coupling comprises a male coupling member 91 having an abutting end face formed with a hollow cylindrical fitting projection 95, a female coupling member 92 having a fitting recessed portion 96 circular in cross section and formed in a fitting end face thereof, an annular gasket 93 interposed between the two coupling members 91, 92, and a retainer 94 for holding the outer periphery of the gasket 93 to hold the gasket 93 to the female coupling member 92. The projection 95 of the male coupling member 91 is formed in its projecting end with a gasket accommodating annular cavity 100. The circular recessed portion 96 of the female coupling member 92 has a retainer holding cylindrical portion 97 formed in its projecting end with a gasket accommodating annular cavity 101. The bottom surfaces of the caved portions 100, 101 are formed with gasket clamping annular projections 98, 99, respectively.
Each of the coupling members 91, 92 may be a connecting block, massflow controller main body or a block joined to the on-off valve. One of these coupling members 91, 92 is of the male type, and the other member is of the female type The fitting projection 95 of the male coupling member 91 is fitted in the recessed portion 96 of the female coupling member 92, whereby the members 91, 92 are prevented from shifting radially relative to each other. The retainer 94, holding the gasket 93, is attached to the cylindrical portion of the female coupling member 92 to ensure a sealing function.
The conventional fluid coupling described includes two types of coupling members, i.e., male and female, so that when these members are to be joined, each member needs to be identified to distinguish the orientation thereof for the joint. The joining procedure therefore takes much time, while when the orientation of the joint is to be reversed, there arises a need to use additional coupling members of reverse male-female relationship.
If the distinction between the male and female types is eliminated, the advantage of preventing radial displacement by the fitting engagement is no longer available, with the result that the female coupling member 92 becomes radially shiftable relative to the male coupling member 91 In the case of the female coupling member 92 having the gasket-holding retainer 94 fitted around its cylindrical portion 97, the gasket clamping projection 99 thereof is unlikely to become radially displaced relative to the gasket 93, whereas with the male coupling member 91 to which the retainer 94 is not attached, the gasket clamping projection 98 thereof is liable to shift radially relative to the gasket 93. Consequently, this gives rise to the problem that the clamping projection 98 becomes released from the gasket end face to impair the seal.
This type of fluid coupling further has the problem of permitting leakage of fluid when subjected to a bending force. Additionally, for the coupling to be suitable to uses of which a very high degree of cleanliness is required as in manufacturing semiconductors, a problem still remains to be solved as to what configuration is to be given to the gasket clamping annular projections.